Fix someThreadSafety::InstanceVariableInClassMethod false positive offenses

[viralpraxis]

Fixes #28, fixes #16, fixes #13

Detecting Data.define, Struct.new and Class.new is essentially the same as detecting define_method ancestors.

NOTE: there is a common issue for both new and existing logic: we do not check if new-lexical-scope-ancestor is also an ancestor for class method. See https://github.com/viralpraxis/rubocop-thread_safety/blob/9a7e9437aadaf3f6fdbe5e847c19542361f6cd92/spec/rubocop/cop/thread_safety/instance_variable_in_class_method_spec.rb#L108 for false negative example

I'll try to evaluate performance impact and check if it the issue mentioned above is fixable

[mikegee]

Thanks!

[viralpraxis]

I'll try to evaluate performance impact and check if it the issue mentioned above is fixable

Done.

@mikegee mind taking a look at this once again?

[viralpraxis]

Alright, hope it's OK to merge 🙂